Documents uncovered by the son of one of the victims suggest that officials were aware the products were high-risk as early as 1983. Jason Evans, 27, whose father Jonathan died in 1993 after being given HIV-infected products, has spent the past year trawling freedom of information responses and official archives.
One of the most damning pieces of evidence is a memo of a meeting of senior officials at the Department of Health in July 1983. They agree there is a particularly high risk from products bought from New York and Los Angeles.
Evans, a marketing consultant from Coventry, uncovered a letter written by Joseph Smith, then director of the National Institute of Biological Standards Control to a senior doctor who was also at the meeting.
It reads: "I ask that the recommendations remain confidential largely because of the commercial implications."
Another document reveals that the Government was warned the products were harmful by the Council of Europe as early as June 1983. Yet officials continued allowing them to be used in the NHS until mid-1985.
There is evidence of a cosy relationship between some of the doctors prescribing the blood products and the drug firms supplying them.
One, who was based at the Newcastle Royal Infirmary, was paid consultancy fees and sponsored for research by the manufacturer Baxter. Other records show that drugs giants donated to the Haemophilia Society.
Evans is preparing a civil claim of negligence and breach of statutory duty against the Department of Health and other organisations who may have been involved in the cover-up. If he is successful, it would pave the way for thousands of victims and families to launch similar compensation cases.
His evidence will be featured in a BBC Panorama documentary to be screened tonight.
Evans said: "The Government knew for sure these products would infect people and they didn't tell anybody.
"It could be an extremely important case. If successful we'll set a precedent. My first memory of my dad is the last time I ever saw him.
"It was my birthday, I was 4 years old and I remember walking into the room and he was on a bed. I remember looking at him but not really understanding what was happening."
The products bought from the US contained plasma that enables the blood to clot and act as a treatment for haemophiliacs.
But many samples had been taken from high-risk donors.
Dr Brian Colvin, who was the director of the haemophilia centre at the Royal London Hospital from 1977 to 2007, said: "We understood there were risks. But what we didn't understand was the magnitude of what was about to happen."
He said haemophilia care would have collapsed had the products been withdrawn.
Dr Mark Winter, who directed the Kent Haemophilia Centre from 1983 to 2010, said very difficult decisions had to be made.
"You don't go into medicine and train to be a doctor to harm people," he said.
"In my case the treatment I gave not only didn't help, it actually killed patients. It was absolutely desperate to see a group of people who were being harmed by their treatment."
He said without the treatment, many haemophiliacs could have died. When Winter's patients were tested for HIV, 30 out of 31 tested positive.
Des Collins, a solicitor who is representing victims and families, said the actions of the Government were shameful. "Not only did they allow these patients to continue being treated, they are now refusing to own up to what has happened," he said.
Last month former health secretary Andy Burnham called for a public inquiry. He said separate evidence had come to light suggesting doctors and public officials had been involved in a criminal cover-up.
